The appeal of extending your truck’s oil drain intervals beyond the manufacturer recommendations is easy to see: It’s both a cost-saving and time-saving measure, and it does make sense in a lot of applications. However, it’s important to remember that manufacturer oil drain intervals are set for a reason, and that while extending them may work in some applications, it’s not recommended for everyone. The consequences of deviating from the recommendations can range from minor setbacks to potentially catastrophic issues.

“Unless all factors are considered, over-extending engine oil service intervals can mean risking engine life and possibly losing engine warranty coverage,” warned Mark Betner, heavy-duty sales manager for Citgo. “The challenge for some equipment owners today is having all the necessary information to make a confident decision when scheduling oil change intervals. Some equipment managers may choose to take an overly conservative approach by changing ahead of the engine manufacturer recommended oil change interval, whereas others take a riskier approach and go beyond the engine manufacturer’s recommendations. Either case can represent significant risk or higher maintenance costs as a result of either not knowing or taking into consideration all factors.”

Each engine manufacturer with whom FE spoke for this piece was quick to point out that the oil drain intervals are set to maintain the life of the engine as long as possible and maximize customer uptime.

“Exceeding recommended oil change intervals can lead to accelerated engine wear as the lubricity of the oil degrades,” said John Moore, Volvo Trucks product marketing manager for powertrain. “Corrosive wear can take place as oxidation sets in.”

Read more about how manufacturer oil drain intervals are set here.

But let’s say you want to extend the oil drain intervals of the trucks in your fleet, and the trucks are in an application where this will likely cause no harm. How do you know for sure? There are three things you need to do before making the decision:

First, it’s important to first talk with your engine manufacturer before extending your oil drain interval. This point was hammered home by each person FE talked to for this story. Additionally, it’s probably a good idea to talk with your oil supplier as well.

Second, the decision to extend the interval should be supported by used oil analysis, which we’ll get to a little bit later on in the story.

Third, make sure your application is a fit for the extended interval. Dan Arcy, global OEM technical services manager for Shell Lubricants, pointed out that the duty cycle of the engine is a major factor in adjusting an oil drain interval, noting that many manufacturers will recommend oil drain intervals based on the fuel consumption of your engine.

“So,” he went on, “if you have lower fuel consumption, you’re able to extend the drain interval to longer than it would be in a more severe operation, where you are consuming a lot more fuel because you’re generating more power out of that engine.

“If you think about a truck that, let’s say, is fully loaded at 80,000 lbs. all the time, it’s going to use more fuel than a truck that’s carrying something light like produce, and maybe only loaded to 60,000 lbs.,” he elaborated. “That truck is not working as hard as the one that’s loaded to 80,000, and it’s going to get much better fuel economy than the one that’s loaded to 80,000. And because it’s not working as hard, you’re able to go with a drain interval that’s longer.”

A variety of factors are considered before giving the fleet the go-ahead to extend the engine oil drain interval. Among them: How consistent is your truck’s duty cycle? The more consistent the route it runs is, the more suited it is for an extended oil drain interval. Trucks that constantly run different routes and don’t stick to a schedule would not be considered candidates for this.

Additionally, what are the details of the truck’s route: the climate, the terrain, the payload, the speed? All of these aspects are important in making the determination.

“Oftentimes fleets want to have something that’s standardized across the system. They don’t want to have one set of trucks that they’re changing at 40,000 miles, one they’re changing at 50,000 and another they’re changing at 60,000—they’d like to establish one drain interval and keep it across the board,” Arcy pointed out. “And what I try to say is: what’s the worst-case scenario for your fleet? Let’s establish an optimum drain interval for that. Better safe than sorry.”

“We encourage our fleet customers to review any drain extension program with us first. While Detroit doesn’t have a formal program to extend oil drain intervals, our team is available to serve as advisors to help minimize equipment risks,” said Greg Braziunas, manager of transmission, clutch, fluids and test planning for Daimler Trucks North America.

Braziunas added that before deciding to extend its oil drain intervals, Detroit recommends that fleets:

• Review its current maintenance program to ensure oil changes are performed properly and on time.
• Assess operations. The best way to decide on oil drain intervals is to review your fleet’s fuel consumption data. High idling intervals, high load factors and chronic mechanical problems are not conducive to extending oil drain intervals.
• Select oil suppliers that have the expertise and products to support an extended oil drain interval program.
• Use only Detroit genuine oil filter products, as these are proven to provide the necessary filtration even under extended drain intervals.

“International offers an extended oil drain interval program that can allow a customer to operate an A26 up to 70,000 miles before an oil change is required,” pointed out Jim Nachtman, on-highway product marketing director for International Trucks. “This program is based on oil sampling, review, and approval with International. This program can reduce the cost of oil and filter changes by up to 40%.”

Additionally, Citgo’s Betner cautioned: “Do not depend only on the claims of engine oil or filter manufacturers who may claim you can extend your oil change intervals based on their performance claims without consideration to all the factors. There are many stories of fleets who bought into an overextended oil change interval claim based on insupportable or insufficient information, only to be met with premature engine failures down the road.”

Read about how the new CK-4 and FA-4 oil categories are impacting oil life here.

Used oil analysis

One of the most important components of extending an oil drain interval is doing used oil analysis. In fact, Corey Trobaugh, corporate materials science and technology leader for Cummins, singled it out as the most important information in making the decision of whether to extend the drain interval, and others we interviewed agreed.

“If you’re looking at extending your drain interval,” Shell’s Arcy began, “we’re definitely going to want to see used oil analysis, and we try to have a baseline analysis, you take a representative number of vehicles from the fleet—at minimum five—and do oil analysis at the normal first drain interval to get a baseline of where they are. Then you slowly increase the drain interval out to the new target, and take samples along the way to make sure that nothing’s changing and they’re still operating in a way that’s going to protect the engine.

“One of the things that I’d be looking at is how much the oil is oxidizing,” he elaborated. “This would be a clear indication of when the oil is getting toward the end of its useful life. I’d also be looking at the wear metals we see in the used oil analysis. We’ll look at the rate of change as they accumulate miles on the oil. As an example: if the engine uses lead in its bearings, sometimes if you get out to the oil drain point, you see a change in the rate of lead that shows up in the oil. And that’s because the oil becomes more acidic in nature as it’s accumulating hours and miles. You start to see the acids that are formed during combustion react with the bearings in the engine, and you see that lead being leeched out into the oil.”

Beyond extending your drain interval, the oil analysis process has other benefits as well. Doing oil analysis can give you a jump on identifying potential contaminants or maintenance issues before they become serious.

“Oil is the lifeblood of the engine,” Volvo’s Moore opined. “Just as in the human body, analyzing it can reveal problems with the oil itself or internal components. Catching major issues like these ahead of time can stop failures from occurring on the road and improve uptime.”

Citgo’s Betner pointed out that engine coolant contamination represents up to 40% of premature lubrication related engine failure problems and often goes undetected. Additionally, he noted, oil analysis can provide engine warranty support, and can be included with the engine service records to improve unit resale value.

“Used oil analysis is like a blood test for the engine,” Cummins’ Trobaugh said. “It offers the fleet a great deal of information. If the oil analysis shows abnormally high sodium contamination, that could indicate a coolant leak, either through the EGR cooler, cylinder liner or cylinder head. With oil analysis, the fleet can also identify which trucks are running outside the normal range for the fleet. For example, if one truck has a higher than average oxidation rate, it could mean it’s running with higher PTO.”

Trobaugh went on to tout Cummins’ OilGuard program, which was launched in 2017 to help fleets who want to extend their oil drain interval. According to Trobaugh, the way it works is that the Cummins OilGuard team will complete an assessment of the fleet, then the Cummins chief engineer examines the data with the OilGuard team and offers their approval of the extension. This new extended oil drain interval now applies to the entire fleet of trucks that fall within the same duty cycle as the test units.